The present invention is directed to improvement of so-called collector type writing instruments, such as ball-point pens, felt tip pens, markers, fountain pens, small-tube writing instruments and the like, having a writing point at the front end thereof, an ink tank for directly storing ink and a collector or grooved adjuster for absorbing variation in internal pressure. In particular, the present invention relates to improvement of the mechanism to solve the flooding problem occurring when a collector type writing instrument is used under conditions in which a sharp pressure variation occurs such as on an airplane.
Writing instruments which have a collector 6 as an internal pressure adjuster, disposed between a conventionally existing point assembly 1 and ink tank 3, for retaining free-state ink 2 and adjusting the pressure inside ink tank 3 so as to prevent ink leakage from a tip 9 of point assembly 1 and ink flooding from an air hole 10 have been known (see FIG. 27). A collector type writing instrument can adjust the internal pressure balance by holding ink 2 of a relatively low viscosity from ink tank 3 within retaining grooves 13 formed in collector 6 and returning ink to ink tank 3, meaning that it provides the function of protecting the writing point from the influence of changes in pressure. A collector type writing instrument has excellent performance such as capabilities of providing an ample amount of ink, securing the stable amount of ink flow down to the last drop and allowing for the amount of ink 2 left to be checked from the outside.
However, since the collector type writing instruments store ink 2 directly and allow movement of ink 2 to and from collector 6, there is a serious drawback that ink 2 will flood outside through air hole 10 of the writing instrument there being no space for withholding ink 2, thereby polluting fingers or clothes if the writing instrument is exposed to an environment in which the ink inside collector 6 exceeds the maximum capacity of retention, which is the limitation of the internal pressure adjustment capacity. As the countermeasures for solving this problem or increasing the safety to some degree, it is possible to make collector 6 greater in capacity or make ink tank 3 smaller. There have already been writing instruments sold on the market which use a collector capable of preventing ink flood under usual environments, meaning gentle temperature changes and the like.
As the current situation is that collector type writing instruments use rather thick barrels, taking a safety margin into account, use of a thicker barrel than the present situation makes the instrument difficult to grip and loses the stylishness. When ink tank 3 is made smaller, reduction of ink stored makes the life short. When the normal collector 6 is made longer, the ink head H becomes higher because the ink head H acting on point assembly 1 is proportional to the height from the air/liquid exchanger 18 to the tip 9 of the writing assembly, hence forward leakage of ink 2 from tip 9 occurs due to gravity.
On the other hand, when a writing instrument which has been capped under about 1 atm. on the ground and is uncapped inside an airplane in which the air pressure is generally reduced to about 0.8 atm., the interior of the pen which has been balanced under 1 atm., is instantaneously exposed to an environment of about 0.8 atm., so ink 2 inside moves in a rush and floods the space around the air channel of collector 6, whereby ink 2 floods out from air hole 10, being unable to be properly retained by the whole part of retaining grooves 13. In order to solve the flood problem occurring under conditions in which the air pressure varies, devices and inventions have been disclosed in Japanese Utility Model Publication Hei 3 No.31580, Japanese Utility Model Publication Hei 3 No.31581 and Japanese Patent Application Laid-open Hei 9 No.104194, and others. However, these disclosures only provide the function of blocking the flush to directly reach the air hole, which is not efficient enough, hence a further effective improvement or other ways to reach a solution have been demanded.
There has been an invention which uses an air supply pipe and the like as disclosed in Japanese Patent Application Laid-open Hei 4 No.227886. However, the conventional invention has the problem that the instrument cannot write continuously unless the writing element is turned down-side up for ink supply and also has the problem of ink capacity being only half filled up from the beginning. Therefore, it is necessary to add such usage instructions or explanation as to the initially reduced amount of ink, for the consumers. Since it is considered that the instrument may be used in an environment in which sharp increase and reduction in air pressure repeatedly occur as in the situations where the instrument is carried over from one airplane to another or from low temperature outdoor air to the front of a heater, there have been demands for excellent free-ink collector type writing instruments which do not need any usage explanation to consumers as above, adopt effective countermeasures against such repeated changes and still can provide beneficial writing comfort (writing performance) making use of low-viscosity ink.
Further, since collector type writing instruments have the problem that the life of writing abruptly ends when ink runs out, it is necessary to carry a spare if the writing instrument has a low amount of ink. There is a demand for collector type writing instruments which can provide an ample amount of ink, which is the main feature of collector type writing instruments, until nearly the end of writing and can provide the performance of a fabric sliver type instrument, which delivers gradually reducing amounts of ink, for a short time so that the pen can be used to take some notes after the last drop of ink is used up. There are also other problems, including the problem of ink dropping from the writing point making it difficult to write when the pen has been kept upside down for long time and the problem of ink leaking forwards due to deficiency of the inherent function of a collector type writing instrument because ink drops and the air/liquid exchanger dries when the pen is held with its tip up and the air/liquid exchanger cannot be wetted again with ink even when the pen is returned with its tip down if there is a part in the way that blocks ink. Even when an equal amount of ink is loaded, a collector type writing instrument delivers a greater amount of ink than a conventional fabric sliver type writing instrument and hence has a shorter life. Therefore, there is a demand that downsizing of the ink tank volume should be avoided as far as possible. There is a demand for solving these problems.
As ink 2 is consumed during writing, collector type writing instruments are adapted to take external air into the ink tank 3 side through air/liquid exchanger 18 so as to avoid reduction in internal pressure (FIG. 27). Therefore, it is usually necessary to provide a space in the rear of collector 6 for allowing free movement of air bubbles. As conventionally disclosed in Japanese Utility Model Application Laid-open Sho 59 No.184682 and other publications, there are configurations in which a solid article such as an ink absorber etc., is arranged in the ink tank, in contact with the rear of the collector. In such a configuration, if air bubbles arising at the air/liquid exchanger do not pass through the ink absorber, which is wetted with ink, without resistance, the ink absorber itself will function as a second air/liquid exchanger, whereby the internal pressure inside the writing instrument lowers, causing ink starvation and other writing deficiencies.
To solve the above problem, it is necessary to provide an arrangement which will not confine the rear of the ink collector or any other countermeasure. However, the air/liquid exchanger in the collector is usually provided at a single site, meaning that the position of the air/liquid exchanger should be well adjusted to that of the air bubble passage of the ink absorber when assembled. Further, the ink absorber and other parts may move forwards due to being dropped or other impacts, so that the space for allowing movement of air bubbles is displaced or the air flow channel for relieving air from the ink tank when a sharp change in pressure occurs becomes narrow. Thus, solution to these problems is wanted.
It is therefore a main object of the present invention to provide improvement of collector type writing instruments. In detail it is an object to provide a writing instrument which, without the necessity of a special configuration limiting the usage, can avoid crucial accidents such as pollution of consumer""s clothes or fingers, due to forward leakage of ink 2 from tip 9 of point assembly 1 or flooding of ink 2 from air hole 10 exceeding the limit of the pressure adjustment capacity of collector 6, by absorbing the variation in pressure inside ink tank 3 resulting from change in temperature or air pressure.
There has been a demand for solution to the defect of collector type writing instruments, i.e., the liability to cause flooding especially when they are used on an airplane or under an environment in which sharp temperature change occurs, therefore it is an object to provide an inexpensive collector type writing instrument with the above problem removed while the appearance and writing distance(life) are maintained as before.
In general, collector type writing instruments include ball-point pens, fountain pens, small-tube writing instruments which have an ink feeder core (center core 8 and/or collector core 7) for assuring the flow path of ink 2 having a low viscosity(100 mPaxc2x7s or lower) from an ink tank 3 to a writing point 9 provided at the tip of a point assembly 1 or which have an ink feeder portion made up of a slit(in the case where a vertical groove 14 is extended to the tip) in a collector 6, and felt tip pens, markers and the like in which center core 8 or collector core 7 itself serves as a writing tip 1. Hereinbelow, ink feeder cores(center core 8, collector core 7, etc.) will also include those which themselves serve as pen tips.
Arranged between ink tank 3 of a cup-like shape having a bottom integrally formed or assembled with a separate part such as a tail plug or the like and a point assembly is a collector 6, which may be formed of a plurality of retaining grooves 13 (generally, gaps defined by a plurality of vanes 12), an air groove 15 connected to the external air and a narrow longitudinal groove 14 creating communication between retaining grooves 13 or which may be made up of a fiber bundle, so as to retain ink 2 using capillarity. An air/liquid exchanger 18 of a small enough size is provided for collector 6 and is adapted to be wetted with ink 2, so that ink tank 3 can be isolated from the external air and air will not enter ink tank 3 from the outside other than through air/liquid exchanger 18.
In the present invention, a collector writing instrument is first provided with a snorkel 25, as an effective means of the present invention, which has a tubular vent portion 27, formed integrally or by assembly of parts, for releasing the air expanded in the rear part inside ink tank 3 to the collector 6, 6a side to thereby prevent application of pressure on ink 2. This arrangement functions as an effective means to prevent ink from flooding when ink 2 has been consumed to some degree or the air inside ink tank 3 occupies the interior space to a certain degree in a state where point assembly 1 is placed downwards. The snorkel 25 is formed integrally or as a separate part, with a sectioning portion 26 for virtually separating ink tank 3, so that air can be easily ventilated through vent portion 27 of snorkel 25. An ink conduit 30 made up of a groove, hole or the like having a smaller size than that of vent portion 27 is formed in either sectioning portion 26 or the ink tank inner wall or both.
As another effective means of the present invention, an ink absorber 31 made up of a fabric sliver, sponge, fiber bundle, foamed material, or the like capable of retaining ink is incorporated in ink tank 3 and connected to center core 8, collector core 7 or longitudinal groove 14 for leading ink 2 from ink tank 3 to point assembly 1. Ink absorber 31 is configured so that its length at least reaches to a position more rearward than the approximate center of ink tank 3 and its radial dimension is sized so as to create a space around itself for permitting free-state ink 2 to move freely. Further, the ink absorber is configured so as to be able to absorb ink 2 from both the front and rear parts, divided by the aforementioned sectioning portion 26 of snorkel 25. As ink absorber 31, a fiber bundle core which is formed by bonding or forming ordinary fibers with adhesives or with heat, a fabric sliver made up of soft fibers covered by a cladding, a continuous-foamed sponge and others can be used. In order to use ink 2 efficiently, necessary methods such as lowering the capillarity to a level smaller than that of center core 8 and collector core 7 may be employed as appropriate.
In order to avoid reduction in the ink capacity of ink tank 3, it is preferred that the volume of snorkel 25 itself is as small as possible. In the present invention, it is possible to avoid the barrel size becoming inefficiently greater if the parts are made as slim as possible by thinning unnecessary walls and shapes after achievement of the above means. From this viewpoint, vent portion 27 and sectioning portion 26 were designed so that these parts could be laid out by combination of ink absorber 31 and ink tank inner wall 34, whereby redundant parts were cut off to increase the capacity of ink tank 3.
As a further effective means of the present invention, in order for air bubbles, which are formed when air enters ink tank 3 through air/liquid exchanger 18 of collector 6, 6a from the outside during writing, to be able to move to the rear space without receiving significant friction from the aforementioned ink absorber 31 and snorkel 25 etc., a clearance portion 42 is provided between the collector 6, 6a and snorkel 25. When the writing instrument is dropped with its front first, the inner parts of the writing instrument will move forwards. Since it is difficult to fix ink absorber 31 because it is formed of a fiber bundle or the like, and since it absorbs ink and hence gains weight, it is preferred if some kind of movement preventing means is provided.
In view of what has been described above, in the present invention, a spacer portion 43 having a projection 44 or air bubble passage channel 45 shaped so as to limit the size of the aforementioned clearance portion 42 is provided. This clearance portion 42 is to secure the space for permitting air bubbles arising from air/liquid exchanger 18 to smoothly pass into ink tank 3. Particularly, this structure is provided in order to limit the movement of the contents due to its being dropped or to protect deterioration of writing performance even when the contents have moved.
Further, ink tank 3 incorporates an ink absorber 31 capable of storing ink so as to connect ink to a center core 8 or a collector core 7 which leads ink from ink tank 3 to point assembly 1, and the ink absorber 31 is configured so that its length at least reaches to a position more rearward than the approximate center of ink tank 3 and its radial dimension is sized so as to create a space around itself in ink tank 3 for permitting free-state ink 2 to move therein and out thereof. The ink absorber 31 is configured so as to be able to absorb ink 2 at least through its front and rear openings, and the spacer portion 43 is formed with an air bubble passage channel 45 that will not block at least part around the front end of ink absorber 31 and an abutment 47 for limiting forward movement of ink absorber 31. Since spacer portion 43 has air bubble passage channel 45 that will not block at least part of the front end of ink absorber 31, air bubbles can smoothly move into ink tank 3. Since provision of abutment 47 limits forward movement of ink absorber 31, it is also possible in this case to secure a space through which air bubbles are allowed to move smoothly.
This spacer portion 43 may be formed as a separate part but can be integrally formed at the rear end portion of collector 6, 6a, so as to reduce the number of parts.
The clearance portion 42 also functions as the air passage for releasing air of a relatively high inner pressure inside ink tank 3 when the ambient environment around the writing instrument is relatively low in pressure.
As an effective means of the present invention, the parts present from sectioning portion 26 to the rear end of collector 6, 6a, except ink tank 3 are integrally molded with, fixed close to with a small enough gap therebetween or fixed in contact with, at least one of ink tank 3, sectioning portion 26 and the collector while the parts present from sectioning portion 26 to the rear end of the collector except ink tank 3 are laid out so that ink 2 will be able to spread and wet the surfaces of all the parts other than inner wall 34 of ink tank 3.
In sum, when the writing instrument is put downwards during normal writing, air/liquid exchanger 18 can be wetted with ink 2 which flows from ink tank 3 to the exchanger via the rear end of collector 6, 6a. Accordingly, it becomes possible to positively achieve the function of a so-called collector writing instrument, by creating a reduced pressure state inside ink tank 6, 6a, making use of a small-diametric meniscus mechanism.
As the second means of the present invention, an ink absorber 31 made up of a fabric sliver, sponge, fiber bundle, foamed material or the like capable of retaining ink is incorporated in ink tank 3 and connected to center core 8, collector core 7 or longitudinal groove 14, in order to lead ink 2 from of ink tank 3 to point assembly 1. Ink absorber 31 is configured so as to at least reach to a position more rearward than the approximate center of ink tank 3 and so that ink can be absorbed through at least both the front and rear parts of ink absorber 31. As ink absorber 31, a fiber bundle core which is formed by bonding or forming ordinary fibers with adhesives or with heat, a fabric sliver made up of soft fibers covered by an unabsorbent cladding, a shaped mass of foamed sponge and others can be used. In order to use ink 2 efficiently, necessary methods such as lowering the capillarity to a level smaller than that of center core 8 and collector core 7 may be preferably employed as appropriate.
When the writing instrument is assembled or when the writing instrument is put with its tip downwards, it is preferred that the above ink absorber 31 and snorkel 25 will not move easily, in order to stop the contents rattling or in order to positively retain absorbed ink 2.
In the present invention, snorkel 25 is formed with a holder portion 46 producing friction against ink absorber 25 so as to hold it with a strength at least greater than that which will stop ink absorber 31 falling due to gravity when the writing instrument is put stationarily.
Holder portion 46 is constructed so as produce a frictional force (preferably the frictional force should be equal to or greater than the weight of the ink absorber plus the weight of ink and equal to or lower than 100 N under which easy assembly is assured and the frictional force ranging 3 N to 30 N is more preferable.) against ink absorber 31, which is equal to or greater than the weight of ink absorber 31 so that the ink absorber 31 will not move when the writing instrument remains stationary. Specifically, undercuts or a small-diametric portion was formed integrally with snorkel 25 or as a separate part so that ink absorber 31 could be press fitted.
If the writing instrument is dropped with its front side down (point assembly 1 down), it often happens that the inner parts inside the writing instrument move forwards causing deficiencies. Since it is difficult, however, to fix ink absorber 31 because it is formed of a fiber bundle or the like, and since it absorbs ink and hence gains weight, it is preferred if some kind of movement preventing means is provided. Further, when considering the conveyance during assembly, it is necessary that ink absorber 31 and snorkel 25 will not move at least due to gravity. It is preferred and important that they will not move even upon its being dropped. As the third effective means of the present invention, ink tank 3 incorporates an ink absorber 31 capable of storing ink so as to connect ink to a center core 8 or a collector core 7 which leads ink from ink tank 3 to point assembly 1, and the ink absorber 31 is configured so that its length at least reaches to a position more rearward than the approximate center of ink tank 3 and so as to be able to absorb ink through front opening 28 and rear opening 29, and the snorkel 25 has an abutment 47 for at least stopping ink absorber 31 from moving forwards (toward the point assembly).
As the fourth effective means of the present invention, vent portion 27 of snorkel 25 has front opening 28 and rear opening 29, and the front opening 28 opens at a position around ink conduit 30 or more frontward and closer to the point assembly 1 side than ink conduit 30 while the rear opening 29 opens at a position more rearward, with respect to the axial direction, than ink conduit 30 and the arrangement is configured so that relations Ts greater than Is and Tt greater than It hold, where xe2x80x98Tsxe2x80x99 is the total minimum cross-section of vent portion 27, xe2x80x98Ttxe2x80x99 is the total distance of the vent portion, xe2x80x98Isxe2x80x99 is the total minimum cross-section of ink conduit 30 and xe2x80x98Itxe2x80x99 is the total distance of the ink conduit. The total minimum cross-section is the sum of minimum cross-sections on the assumption that there are a number of conduits or vents. The total distance is the sum of distances(the total unfolded length including zigzag or bent paths) and the like, similarly on the assumption that there are a number of conduits or vents.
In one word, vent portion 27 is configured so that it will produce less flow resistance against flow of ink 2 or air than ink conduit 30 does and so that ink 2 will easily and naturally flow from ink tank 3 to the collector 6, 6a side when point assembly 1 is set downwards. Snorkel 25 can be formed of resins such as transparent ABS, AS, PS, PP, PE, PET, PC, transparent PA and others, and these resins kneaded with additives such as surfactants and the like, various alloys. Anyway, the snorkel is a molding of materials which contain transparent resins having resistance to ink.
As fifth effective means of the present invention, an ink absorber 31 made up of a fabric sliver, sponge, fiber bundle, foamed material, or the like capable of retaining ink is incorporated in ink tank 3 and connected to center core 8, collector core 7 or longitudinal groove 14, in order to lead ink 2 from the interior of ink tank 3 to point assembly 1. Ink absorber 31 is configured so that its length at least ranges from a position more frontward to a position more rearward with respect to the approximate center of the portion where free-state ink is stored in ink tank 3, and ink absorber 31 can absorb ink 2 from both its front and rear parts. As ink absorber 31, a fiber bundle core which is formed by bonding or forming ordinary fibers with adhesives or with heat, a fabric sliver made up of soft fibers or continuous-foamed sponge covered by an unabsorbent cladding can be used. In order to use ink 2 efficiently, necessary methods such as lowering the capillarity to a level smaller than that of center core 8 and collector core 7 may be employed as appropriate.
As the sixth effective means of the present invention, a space which allows ink 2 to flow and permits the amount of ink 2 left to be checked from the outside is created around ink absorber 31 by transparent ink tank 3, collector 6, 6a, and ink absorber 31 while rear opening 29 of snorkel 25 is made to open at the approximate center (preferably at around the centroid of the ink storage portion) of the portion where free-state ink is stored in ink tank 3 and front opening 28 of snorkel 25 is made to open at a position around the rear end of collector 6.
Here, relation 3:K greater than Tsxc2x7Tt greater than 0.01xc2x7Y greater than Isxc2x7It and relation 4:Is greater than 2xc2x7Bxc2x7B (greater than two times of B squared) hold, where xe2x80x98Tsxe2x80x99 is the total minimum cross-section of the vent portion, xe2x80x98Ttxe2x80x99 is the total distance of the vent portion, xe2x80x98Isxe2x80x99 is the total minimum cross-section of the ink conduit, xe2x80x98Itxe2x80x99 is the total distance of the ink conduit, xe2x80x98Yxe2x80x99 is the maximum ink capacity of the ink tank, xe2x80x98Kxe2x80x99 is the maximum ink retention capacity of the collector and xe2x80x98Bxe2x80x99 is the minimum width of the air/liquid exchanger. Here, the total minimum cross-section and the total distance are defined in the same way as above.
The knowledge that the collector will work well if its retention capacity is set at 10 to 30% of a typical tank volume has been already known. The vent portion volume of snorkel 25 is sized so as be smaller than the collector""s volume and greater than that needed for air bubbles to move. The ink conduit 30 is sized so that air bubbles will be unlikely to move and ink 2 will receive no resistance and be able to move more easily therethrough than they passes through air/liquid exchanger 18 of collector 6, 6a. In other words, the ink conduit is sized so that capillary action for promoting ink communication can be obtained. When the cross-section of ink conduit 30 is formed to be greater than the size of the meniscus (width B squared) of air/liquid exchanger 18, it is possible to eliminate the occurrence of the deficiency that ink 2 will not move from rear tank 38 to front tank 37 by the formation of a meniscus at ink conduit 30 like air/liquid exchanger 18 of collector 6 does.
As the eighth effective means of the present invention, the end of the vent portion of the snorkel is formed with a beveled portion. Provision of such a beveled portion enables air bubbles to easily depart from the rear opening. Thereby it is possible to solve the problems of air bubbles congesting in the vent portion and producing a bad effect on writing performance.